Microbiology of a multi-layer biosolid/desulfurized tailings cover on a mill tailings impoundment

Eva Pakostova, Mason McAlary, Stephanie Marshall, Samantha McGarry, Carol Ptacek, David Blowes

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Abstract

The Strathcona Waste Water Treatment System (SWWTS; Sudbury, ON, Canada) has received mill tailings from Ni/Cu ore processing from 1970 to present. Demonstration-scale, multi-layer cover systems were installed on selected tailings deposition cells at the SWWTS. The cover systems are comprised of an upper layer of organic carbon-rich material, composed of a layer biosolids fertilizer along with composted municipal food and yard waste, then a layer of desulfurized, fine-grained tailings. Organic carbon components used in these covers promote microbial communities that consume O2, thus decreasing sulfide oxidation rates in the underlying tailings. The aim of this study was to investigate the microbiology of the cover systems and the underlying tailings, using a combination of culture-dependent (most probable number) and culture-independent (16S rRNA gene amplicon sequencing) techniques, and assess the impact of the organic component of the cover system four to six years after implementation. Most tailings samples were characterized by circumneutral bulk pH and low concentrations of dissolved metals. The presence of the organic cover resulted in elevated counts of sulfatereducers (by two orders of magnitude, compared to control samples) immediately below the organic cover, as
well as an increased abundance of heterotrophic species (~108 cells g􀀀 1) at greater depth (~4 m) in the tailings profile. Mineral-oxidizing microorganisms were also present in the tailings, with neutrophilic sulfur-oxidizers dominating the samples (mean ~106 cells g􀀀 1). Relative abundances of sulfur- and/or iron-oxidizers determined by sequencing ranged from 0.5 to 18.3% of total reads (mean ~5.6% in amended tailings) and indicated the presence of local microenvironments with ongoing sulfide oxidation. This work provides a detailed characterization
of the microbiology of a tailings impoundment with an organic cover, highlighting the opportunities associated with monitoring microbial processes in such remediation systems.
Original languageEnglish
Article number114030
Number of pages11
JournalJournal of Environmental Management
Volume302
Issue numberPart A
Early online date5 Nov 2021
DOIs
Publication statusPublished - 15 Jan 2022

Bibliographical note

This is an open access article under the CC BY-NC-ND license

Funding Information:
Funding for this research was provided by the NSERC TERRE-NET program (grant NETGP 479708–15 ). The authors gratefully acknowledge financial and logistical support provided by Glencore. In addition, the authors thank Robert Mellow for his assistance on this project. J. Bain, L. Groza, W.D. Gould (University of Waterloo), and J. McBeth (University of Saskatchewan) provided technical assistance.

Funding Information:
Funding for this research was provided by the NSERC TERRE-NET program (grant NETGP 479708?15). The authors gratefully acknowledge financial and logistical support provided by Glencore. In addition, the authors thank Robert Mellow for his assistance on this project. J. Bain, L. Groza, W.D. Gould (University of Waterloo), and J. McBeth (University of Saskatchewan) provided technical assistance.

Publisher Copyright:
© The Authors

Funder

NSERC

Keywords

  • Acid mine drainage
  • Biodiversity
  • Biosolids
  • Dry cover
  • Mine waste
  • Tailings
  • Waste Management and Disposal
  • General Medicine
  • Environmental Engineering
  • Management, Monitoring, Policy and Law

ASJC Scopus subject areas

  • Waste Management and Disposal
  • Management, Monitoring, Policy and Law
  • Environmental Engineering

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